Diamond like carbon coating of substrate housings

ABSTRACT

Embodiments of the invention include articles comprising a diamond like carbon coating or doped diamond like carbon coating on one or more surfaces of a plastic substrate or a plastic enclosure. Embodiments of the DLC or doped DLC coatings reduce the gas permeation of the coated plastic or thermoplastic to hydrogen or helium compared to the permeability of the plastic alone. The DLC or doped DLC coatings coating provides a surface resistivity of from about 10 7  to about 10 14  ohm/square and have a transmittance that range from about 0% to about 70% less than the transmittance of the underlying plastic substrate in the range of about 300 nm to about 1100 nm. The DLC coated plastic can be used in environmental enclosures for protecting environmentally sensitive substrates such as semiconductor wafers and reticles.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/194,636 filed Jul. 29, 2011, which is a continuation of U.S.application Ser. No. 12/515,606, filed Jun. 9, 2009, which is the U.S.National Stage of International Application No. PCT/US2007/013909, filedon Jun. 14, 2007, published in English, which claims the benefit of U.S.Provisional Application No. 60/860,837, filed Nov. 22, 2006, thecontents of which are incorporated herein by reference in theirentirety.

BACKGROUND

Diamond like carbon coatings have a number of unique properties such aslow friction coefficient, high surface hardness and high wearresistance. They have been used in a number of high wear applicationssuch as bearings, medical appliances, as well as food and beveragecontainers.

SUMMARY

Embodiments of the present invention include diamond like carboncoatings (DLC), doped DLC coatings, or combinations including these onplastics that can be made into storage containers to protectenvironmentally sensitive substrates. Such coatings can provide acombination of protection from electro-static discharge (ESD),sufficient transparency to enable a user identify the contents of thecontainer, and gas barrier properties that protect the substrates fromcontamination in the ambient environment or outgassing from thecontainer materials of construction. In some embodiments the diamondlike carbon coating or the doped diamond like carbon coating can befurther modified reduce the contact angle and increase wettability(hydrophilic property) of the diamond like coating; the contact angle islower than that for the starting DLC or doped DLC coating. Improvedhydrophilicity is desirable for cleaning of containers with these DLCcoatings. In some embodiments the dopant in the DLC coating is oxygen,nitrogen, or any combination of these.

Embodiments of the invention include articles comprising a diamond likecarbon coating on one or more surfaces of a plastic substrate or aplastic enclosure. Embodiments of the DLC or doped DLC coatings canreduce the gas permeation of the coated plastic or thermoplastic tohydrogen or helium by more than 10 times compared to the permeability ofthe plastic alone, and the coating provides a surface resistivity offrom about 10⁷ to about 10¹² ohm/square and has a transmittance thatranges from about 0% to about 70% less than the transmittance of theunderlying plastic substrate for light in the range of about 300 nm toabout 1100 nm. Other embodiments of the invention can comprise orconsist of a substrate enclosure having at least one diamond like carbonor doped diamond like carbon coated surface on a thermoplastic of theenclosure. The diamond like carbon or doped diamond like carbon coatedsurface has a surface resistivity in the range of from 10⁷ ohm persquare to 10¹⁴ ohm per square and a percent transmittance that is atleast 70% of the thermoplastic from 300 nm to 1100 nm, and a gaspermeation coefficient for helium of 0.59 Barrers or less. Still otherembodiments can be an article comprising or consisting of a plastic orthermoplastic and an adherent diamond like carbon coating on one or moresurfaces of the plastic or thermoplastic. The adherent diamond likecarbon coating has a permeability coefficient for helium gas that is atleast 10 times less than the permeability coefficient for helium of theplastic or thermoplastic. The diamond like carbon coating has a surfaceresistivity of from about 10⁷ to about 10¹⁴ ohm/square and the adherentdiamond like carbon coating has a transmittance that is 0% to 70% lessthan the transmittance of the plastic or thermoplastic to light in therange of 300 nm to 1100 nm.

In some embodiments, the diamond like carbon coating comprises orincludes a doped diamond like carbon on one or more surfaces of apolymeric or a thermoplastic substrate where the substrate can be usedto make an enclosure for environmentally sensitive substrates. In otherembodiments a molded enclosure or portions of it used for protecting oneor more environmentally sensitive substrate(s) can be coated withdiamond like carbon coating or doped diamond like carbon coating of thepresent invention. Such a coating reduces the gas permeation of theenclosure to gases from the environment or contaminants from the plasticused to make the enclosure. The coating can reduce the permeability ofthe underlying substrate to hydrogen gas by more than 100 times and thecoating can provides a surface resistivity of about 10⁷ to about 10¹²ohm/square and has a transmittance that ranges from about 0% to about70% less than the transmittance of the underlying plastic substrate forlight in the range of about 300 nm to about 1100 nm.

The doped diamond like carbon coating on plastic material in embodimentsof the present invention can comprise carbon, oxygen, nitrogen, or acombination that includes any of these that have a transmittance thatranges from about 0% to about 70% less than the transmittance of theunderlying plastic substrate for light in the range of about 300 nm toabout 1100 nm and where the surface resistivity of the doped diamondlike carbon is in the range of from about 10⁷ ohm per square to about10¹⁴ ohm per square; and in other embodiments from about 10⁸ ohm persquare to about 10¹² ohm per square; and in still other embodiments fromabout 10⁹ ohm per square to about 10¹² ohm per square. In someembodiments, the coating is uniform and the variation of surfaceresistivity from one portion of the DLC or doped DLC coated plastic isless than about 10² ohm per square and in some cases less than 10¹ ohmper square over the coated surface. Such coating uniformity isadvantageous because it can eliminate insulating spots from the coatedplastic. Embodiments of the diamond like coating or doped diamond likecarbon coating in embodiments of the invention have lower gas permeationcoefficients compared to diamond like carbon on plastics reported inU.S. Pat. No. 6,805,931. In some embodiments of the invention the amountof nitrogen, oxygen, or a combination of these in the doped diamond likecarbon coatings on a plastic substrate can be chosen to provide apermeation coefficient for hydrogen or helium gas of 0.59 Barrers to0.03 Barrers, or in some embodiments a permeation coefficient of from0.15 Barrers to 0.03 Barrers. In some embodiments of the invention theamount of nitrogen, oxygen, or a combination of these in the dopeddiamond like carbon coatings on a plastic substrate can be chosen toprovide a permeation coefficient for hydrogen or helium gas of 0.12Barrers or less, or in some embodiments a permeation coefficient of 0.06Barrers or less, and in still other embodiments a permeation coefficientof 0.03 Barrers or less. The thickness and composition of the DLC ordoped DLC coating is not limited and can chosen to provide a permeationcoefficient, percent transmittance to light, a surface resistivity, asurface resistivity uniformity or any combination of these as describedherein. In some embodiments the coating thickness can be less than 1micron, in other embodiments 250 nm or less, in other embodiments 120 nmor less, and in still other embodiments 70 nm or less.

In one embodiment of the invention, the substrate or portion of anenclosure with the diamond like carbon or doped diamond like carboncoating in various embodiments of the invention may be characterized inthat the XPS spectra of the diamond like carbon film in embodiments ofthe invention has a carbon peak, an oxygen peak and a nitrogen peak. Insome embodiments, the XPS spectrum has a carbon peak at about 284 eV, anoxygen peak at about 532 eV, and a nitrogen peak at about 399 eV.

The plastic substrate or one or more surfaces of a plastic enclosurecoated with diamond like carbon or doped diamond like carbon in variousembodiments of the invention can further be treated. For exampletreatment can include but is not limited to treatment by a plasma, areactive gas containing plasma, or corona discharge, an oxygencontaining plasma, or other method to further modify the coating to makeit more hydrophilic. The one or more DLC or doped DLC coated surfaces ofan enclosure can be or form any part of a substrate carrier such as butnot limited to a carrier for wafers, a carrier for flat panel displays,or a carrier for lithographic reticles, or a carrier for otherenvironmentally sensitive substrates. The enclosure can provideprotection from electrostatic discharge, environmental gases, particles,outgassing species from enclosure materials of construction, or anycombination that includes these. The DLC or doped DLC coating may bealso be used to reduce electrostatic discharge (ESD) such as insubstrate carriers or fluid handling equipment in contact with flammableliquids such as organic liquids used in semiconductor wafermanufacturing, pharmaceutical manufacturing, or fine chemicalmanufacturing. Such fluid handling equipment can include conduits andtubing, flow meters and controllers and surfaces therein, dispensenozzles, heat exchangers, fluid filters, or transducer surfaces and thelike.

One embodiment of the invention includes the acts or steps ofdetermining a customer's need for environmental protection of sensitivesubstrates such as a semiconductor wafer, a reticle, or flat paneldisplay, and providing an enclosure to the customer with specifiedproperties that can separately include electrostatic dischargeprotection, transparency, gas permeation or outgassing resistance. Insome embodiments a combination of properties can be used to determinethe type of enclosure to be provided or sold to the customer, suchproperties can include any combination of ESD protection (surfaceresistivity), transparency or transmittance of light, gas permeabilitycoefficient, or any combination of properties including these.

One embodiment of the invention can include method comprising selling anenclosure having at least one diamond like carbon or doped DLC coatedsurface with a surface resistivity in the range of from about 10⁷ ohmper square to about 10¹² ohm per square and a % transmittance that is 0%to 70% of the underlying substrate in the visible or UV spectrum, and apermeation coefficient for hydrogen or helium of 0.59 Barrers to 0.03Barrers or less, or from 0.15 Barrers to 0.03 Barrers or less for acoating on both sides of a polymeric substrate. The method can furtherinclude making the enclosures, testing them for permeation, ESD,transmission, or any combination of these and sorting the enclosuresbased on the testing criteria. The sorted enclosures can be sold basedon their ESD properties or any combination of these properties. In someembodiments, the method can further include coating the portions of theenclosure in one or more coating operations to further modify theproperties of the coating.

Another method includes determining client requirements for protecting asubstrate that can include the ESD or surface resistivity, percenttransmittance, gas permeability, or any combination of these. The methodcan further include the step of contacting a central server/database toinput the information for the client's requirements, and coating thehousings with a doped diamond like coating to meet the clientrequirements. The method can further include the step of determining aprice for the housings and providing the client with a price and timefor delivery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of diamond like carbon in an embodiment of theinvention coated on both sides of a 10 mil PC sample, the diamond likecarbon has a coating thickness of 120 nm on each side of the PC sample;FIG. 1A is an exploded view illustrating a plastic film (120) with aregion of a transparent and adherent diamond like carbon coating (130)in an embodiment of the invention, the plastic film (120) is shownoverlaying text (110) on a piece of paper; FIG. 1B illustrates a topdown view of FIG. 1A through the film (120) illustrating that a portionof the text (110A) beneath the region of diamond like carbon coating(130) on the plastic film (120) is visible through the transparentdiamond like carbon coating (130).

FIG. 2A is a XPS spectrum of a doped diamond like carbon coating on apolycarbonate film (untreated by plasma) and FIG. 2B illustrates a XPSspectrum of a doped diamond like carbon coating on a polycarbonate film(treated by plasma), the XPS spectra of these two samples shows a carbonpeak at about 284 eV, an oxygen peak at about 532 eV, and a nitrogenpeak at about 399 eV.

FIG. 3A-FIG. 3D illustrate XPS spectra of embodiments of the invention.FIG. 3A illustrate the C 1s peak in the XPS spectra for the untreatedDLC coating on a polycarbonate film shown in FIG. 2A, the C 1s peak iscentered at about 284 eV and the peak envelope ranges from 282 eV to 286eV; FIG. 3B illustrate the O 1s peak in the XPS spectra for theuntreated DLC coating on a polycarbonate film shown in FIG. 2A, the O 1speak is centered at about 532 eV and the peak envelope ranges from 530eV to 534 eV; FIG. 3C illustrate the C is peak in the XPS spectra forthe plasma treated DLC coating on a polycarbonate film shown in FIG. 2B,the C 1s peak is centered at about 285 eV and the peak envelope rangesfrom 283 eV to 290 eV; FIG. 3D illustrate the O 1s peak in the XPSspectra for the plasma treated DLC coating on a polycarbonate film shownin FIG. 2B, the O 1s peak is centered at about 533 eV and the peakenvelope ranges from 530 eV to 535 eV.

FIG. 4 illustrates a non-limiting flow chart describing a method in anembodiment of the invention.

FIG. 5 is a UV-VIS spectrum of a sample of polycarbonate film (510) anda sample of polycarbonate film with about 120 nm diamond like carboncoating on each side of a polycarbonate film (520) in an embodiment ofthe invention from FIG. 1.

FIG. 6 illustrates a transparent coated reticle dome (610), which is anon-limiting example of a portion of a substrate carrier, that wascoated on the inside surface of the dome with about 120 nm diamond likecarbon in an embodiment of the invention; the coated surface has asurface resistivity of about 10⁹ ohms per square and appears lighterthan the thicker diamond like carbon coating of FIG. 1; the text (630)on background (620) is visible through the transparent diamond likecarbon coating on the surface of the dome (610) as illustrated.

FIG. 7 illustrates a non-limiting flow chart describing a method in anembodiment of the invention.

DETAILED DESCRIPTION

Before the present compositions and methods are described, it is to beunderstood that this invention is not limited to the particularmolecules, compositions, methodologies or protocols described, as thesemay vary. It is also to be understood that the terminology used in thedescription is for the purpose of describing the particular versions orembodiments only, and is not intended to limit the scope of the presentinvention which will be limited only by the appended claims.

It must also be noted that as used herein and in the appended claims,the singular forms “a”, “an”, and “the” include plural reference unlessthe context clearly dictates otherwise. Thus, for example, reference toa “coating layer” is a reference to one or more coating layers andequivalents thereof known to those skilled in the art, and so forth.Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art. Methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of embodimentsof the present invention. All publications mentioned herein areincorporated by reference. Nothing herein is to be construed as anadmission that the invention is not entitled to antedate such disclosureby virtue of prior invention.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not. Forexample, the diamond like carbon coating on a plastic portion of anenclosure may include instances where the coating is doped, is notdoped, or includes a combination of doped diamond like carbon anddiamond like carbon layers.

FIG. 1 is an illustration of a film in an embodiment of the inventionwith a transparent diamond like carbon coating (130) of 120 nm thicknessapplied to both sides of a 10 mil thick polycarbonate substrate (120);the film had a surface resistivity of about 10¹¹ ohm/square. The UV-VISspectrum from about 300 nm to 1100 nm of this diamond like carboncoating on the 10 mil thick PC (520) and the uncoated polycarbonate film(510) is shown in FIG. 5. As shown in FIG. 5, at about 300 nm thepolycarbonate film (510) had a percent transmittance of about 3% and theDLC coated polycarbonate (520) had a transmittance of about 0%—thediamond like carbon coated substrate had a transmittance that was nearlythe same or 0% less than the uncoated polycarbonate plastic; at about400 nm the polycarbonate film (510) had a percent transmittance of about70% and the DLC coated polycarbonate (520) had a transmittance of about2%—the diamond like carbon coated substrate (520) had a transmittancethat was nearly 70% less than the uncoated polycarbonate plastic (510);at about 600 nm the polycarbonate film (510) had a percent transmittanceof about 72% and the DLC coated polycarbonate (520) had a transmittanceof about 10%; the coated substrate (520) had a transmittance that wasabout 60% less than the uncoated polycarbonate plastic (510); at awavelength of about 700 nm the polycarbonate film (510) had a percenttransmittance of about 77% and the DLC coated polycarbonate (520) had atransmittance of about 38%; the coated substrate (520) had atransmittance that was about 40% less than the uncoated polycarbonateplastic (510); at a wavelength at about 1100 nm the polycarbonate film(510) had a percent transmittance of about 80% and the DLC coatedpolycarbonate (520) had a transmittance of about 45%; the coatedsubstrate (520) had a transmittance that was about 35% less than theuncoated polycarbonate plastic (510). This doped diamond like carboncoated plastic substrate (520) is characterized by the XPS spectra inFIG. 2A (untreated), and has a transmittance that ranges from about 0%to about 70% less than the transmittance of the underlying plasticsubstrate in the range of about 300 nm to about 1100 nm. Thetransmittance of the coated sample (520) in FIG. 5 increases linearlybetween about 500 nm and about 900 nm. The low transmission in the UVportion of the spectrum, especially below about 400 nm to 500 nm isadvantageous because for example, it can prevent or reduce the amount ofUV light that contacts an environmentally sensitive surface enclosed bya carrier coated with this diamond like carbon coating. UV light candamage sensitive surfaces and can cause reactions to occur onenvironmentally sensitive surfaces. Such reactions can cause thin filmdamage. As shown in FIG. 1, the coating is sufficiently transparent toview text through the coated film.

A variety of plastic substrates can be DLC coated, doped diamond likecarbon coated, or coated with a combination of these coatings. Forexample polycarbonate substrates can be coated and their surfaceresistivities could be controlled by doping the coating. The dopeddiamond like carbon and the coating was very pure with respect tooutgassing, extractable metals, extractable anions. The doped diamondlike carbons in embodiments of the invention improved the permeationresistance of the coated material compared to the uncoated plasticsubstrate. For example, a 120 nm diamond like carbon coating on bothsides of a polycarbonate substrate reduced the hydrogen gas permeationof the underlying plastic by more than 10 times, in some embodiments bymore than 100 times, and in still other embodiments by more than 300times compared to the uncoated base polycarbonate substrate.

Polycarbonate (PC), Perfluoroalkoxy (PFA), polypropylene (PP), andAcrylonitrile butadiene styrene (ABS) were used as plastic orthermoplastic substrates for coating with the DLC or doped DLC coatings.PC film with 10 and 20 mil thickness (GE) were used and PFA film with 10mil thickness (DuPont, Teflon 1000LP) was used. PP sheet with 57 milthickness and ABS film with 20 mil thickness were purchased fromMcMaster. A silicon wafer was used as a substrate for outgassing andpurity tests.

DLC coatings in embodiments of the invention can be prepared using adoping technology that incorporates controlled amounts of oxygen andnitrogen into the DLC coating. This coating process allows properties ofthe doped diamond like carbon coating, for example the electronicconductivity or resistivity, gas permeability, percent transmission tolight, adhesion to the polymer, combinations of these properties, orother properties of the film to be modified. Embodiments of the diamondlike carbon on a plastic in present invention can comprise or consist ofoxygen, nitrogen, or a combination that includes any of these thatprovide a diamond like carbon coating or a doped diamond like carboncoating on a polymeric substrate whereby the coated substrate has atransmittance that ranges from about 0% to about 70% less (and valuestherein) than the percent transmittance of the underlying plasticsubstrate for light in the range of about 300 nm to about 1100 nm andwhere the surface resistivity of the doped diamond like carbon is in therange of from about 10⁷ ohm per square to about 10¹⁴ ohm per square andvalues therein and the gas permeation for hydrogen or helium gas is 0.59Barrers to 0.03 Barrers or less, or from 0.15 Barrers to 0.03 Barrers orless. The DLC coatings that were doped to control resistivity, percenttransmission, gas permeability and the like were made by Surmet,Burlington, Mass. These films had a composition whose percent atomiccomposition is illustrate in the XPS spectrum as shown in FIG. 2A. Thesefilms could be subsequently treated, for example but not limited to anoxygen plasma, as shown in FIG. 2B to provide higher oxygen content, asevidenced by the percent atomic composition and lower contact angle (seefor example FIG. 2B and Table 5). Three different coatings wereprepared. One film utilized 10 and 20 mil thick PC films as a plasticsubstrate. The target thickness for the DLC or doped DLC coating was 120nm. The second film used PC and PFA as substrates and the target DLC ordoped carbon coating thickness was 70 nm. The third run used PP and ABSas substrates and the target DLC or doped DLC thickness was 120 nm.

In some embodiments, the diamond like carbon coating is applied underconditions in which a portion or all of the coating adheres to theunderlying plastic. The adhesion can include forces such as but notlimited to covalent chemical bonds, or weaker bonds such as hydrogenbonds, dipole interaction, or van der Waals forces, or in someembodiments a combination of these. In embodiments of the invention thediamond like carbon or doped diamond like carbon coating is adherent oradheres to the underlying polymeric substrate when tape attached as asmall strip on the DLC coated plastic does not result in transfer of thecoating to the tape when the tape is removed. In some embodiments theplastic is a thermoplastic material. In other embodiments thethermoplastic is a polyester, polyolefin, a polyimide, polyetherimide, aperfluorinated thermoplastic, polysulfone, a polyetherether ketone, orother material suitable for a wafer, reticle, or other sensitivesubstrate container. In some embodiments the thermoplastic ispolycarbonate. Alternatively, a material such as polyetherimide (PEI)could be used. PEI can provide better dimensional stability than PEEK attemperatures between 150° C. and 200° C. Polymers used in the bulkstructure could be non-conductive (unfilled) or conductive (carbonpowder, ceramic, etc.).

In some embodiments the plastic that is coated with DLC or doped DLC hasa surface energy and roughness such that an integral film is formedexhibiting lower gas permeation coefficient than the underlying plastic.Non-limiting examples of such a material include polycarbonate, blendsincluding polycarbonate, other polyesters, polyphosphonates, and thelike with similar or higher surface energy.

One advantage of the DLC coatings, which includes doped DLC coatings, inembodiments of the invention versus other conductive coatings is theirrelative transparency. The DLC coatings in embodiments of the inventionare sufficiently transparent that they can be seen through asillustrated in FIG. 1, or are sufficiently transparent that an operatorin a semiconductor wafer manufacturing facility could under normalsemiconductor fab lighting conditions determine whether a wafer orreticle enclosure within 1 to 10 meters that was coated with the DLC ordoped DLC coating in embodiments of the invention contained wafers,reticles, or other environmentally sensitive substrates or materials.FIG. 1 illustrates the transparency of a doped DLC coating in anembodiment of the invention on a polycarbonate (PC) film. A two inchdiameter disk of DLC coated PC was laid over the right half of a logo(110) as shown in FIG. 1. Even though the diamond like carbon coating(130) adherent on the polycarbonate substrate (120) in this embodimenthad a yellow brown or brown hue, the portion of the logo (110A) belowthe diamond like carbon coating region (130) was still clearly visiblewhich illustrates that the diamond like carbon coating (130) wastransparent. The coating films in embodiments of the invention can haveother hues and remain transparent. For example, the hue can range fromlight yellow to a light brown hue; other colors and hues are possible.The hue and transparency allow a worker to visually check the contentsof a device handling case under ambient fab lighting conditions for oneor more substrates such as reticles or wafers. An example of such acoating on a plastic substrate used as part of an enclosure isillustrated in FIG. 6. In this example the coating is similar to that ofFIG. 1, however it is only about 120 nm thick and is applied only to thesurface closest to the printed text (630). Visually the embodiment inFIG. 6 is lighter than the embodiment in FIG. 1.

The diamond like carbon coating or doped diamond like carbon coatingthickness can be measured using a test coupon that is partially maskedthat had been placed in the same coating chamber as the plasticsubstrate to be coated. The thickness of the coating can be determinedby profilometry. Two different coating thickness were produced, 120 nmand 70 nm, however embodiments of the invention are not limited to thisrange or these particular values. Other doped film DLC compositions ofdifferent thickness can be made and used provided the films reduce thegas permeability of the substrate, have ESD properties sufficient toprotect wafers, reticles, or other static sensitive devices, havesufficient transparency, or any combination of these. The amount of eachdopant such as nitrogen or oxygen in the film can be changed to meet theapplication requirements. Films can be applied to portions of thecarriers, the entire carrier, or to one or more sides. The thickness andcomposition of the DLC or doped DLC coating is not limited and canchosen to provide a hydrogen gas permeation coefficient, percenttransmittance to light, a surface resistivity, a surface resistivityuniformity or any combination of these as described herein. In someembodiments the coating thickness can be 1 micron or less, in otherembodiments 250 nm or less, in other embodiments 120 nm or less, and instill other embodiments 70 nm or less.

Dopants which can be used in the DLC films can include or consist ofnitrogen, oxygen, or combinations of these. The amounts of oxygen andnitrogen incorporated into the doped DLC coating can be modified duringthe coating process by the amount of nitrogen and or oxygen containingprecursor gases introduced into the coating apparatus. The compositionof the coating can be determined by XPS and the properties of the dopeddiamond like carbon coating on the polymer measured, for example theelectronic conductivity or resistivity, gas permeability, percenttransmission to light, or adhesion of the coating to the polymer. Theelectrical properties can be varied with dopant and amount of dopant inthe film.

Surface resistance of the DLC or doped DLC films on plastic substratesin embodiments of the invention can be measured using surface resistancemeter such as a Monroe Electronics 262A surface resistance meter. For PCsamples, the first run sample (120 nm both sides) showed about 10¹¹ohm/square surface resistivity and the second run (70 nm both sides)sampled showed about 10⁹ ohm/square surface resistivity. In someembodiments the surface resistivity can range from about 10⁷ to about10¹³ ohm per square. For PFA and ABS samples, two sides showed differentsurface resistances and depended on the surface roughness of the sample.Smooth surfaces showed lower surface resistance. PFA showed 10¹¹ and10¹² ohms/sq. The PP sample showed 10¹² ohm/sq on both sides. Thethickness of the film as well as the composition of the dopants in theDLC film can be modified to change the surface resistivity into therange of from about 10⁴ to about 10¹⁴ ohms/square.

The polymeric surface condition can be used to modify the morphology ofthe DLC coating. The morphology of the DLC films can be examined usingoptical microscopy. PP, PFA, and ABS substrates were rough and DLCcoated substrates were observed have many crack-like features on thesurface which might be introduced during the coating process. The PCsubstrate was very smooth and the DLC coated PC substrate provided asmooth DLC coating.

FIG. 4 illustrates a non-limiting flow chart describing a method in anembodiment of the invention. The method can include coating (410) one ormore surfaces of an enclosure or a fluid handling device with a diamondlike carbon coating or a doped diamond like carbon coating and measuring(420) the properties of the coating such as coating thickness, surfaceresistivity or electrostatic dissipative property, percent transmittanceof light, gas permeability, coating adhesion, hardness, or anycombination of these. Based on the testing, the acceptability of thecoating on the enclosure or fluid handling device for a particular useis determined (430). If the coating is acceptable for the use (432) thearticle can be sold or sorted (460) based on the results of themeasurement. In some embodiments the articles can be sorted based onwhether one or more properties measured are within 1%, 2%, 5%, 10%, ormore of the target values for each of the measured properties. Forexample the customer requirement for percent transmittance to 600 nmlight may be 60±2% and permeation coefficient for helium of 0.05±10%Barres. After coating, those articles having 60±2% transmission andpermeation coefficient for helium of 0.05±10% Barres can be grouped forsale; those having higher transmission and or permeability can begrouped for further coating. In some embodiments the articles can besorted based on whether the one or more properties are within a factorof 10, 100, 1000, or more of the other articles coated. For example thesurface resistivity target value for the coated article may be 10⁹ohms/square but those within a factor of 100 or having a surfaceresistivity of 10⁷ ohms/square to 10¹¹ ohms/square would be acceptablefor the use (432) and the article can be sold or sorted (460) based onthe results of this measurement. In other embodiments the articles canbe sorted on their surface resistivity into bins ranging for example butnot limited to 10⁷ to 10⁸ ohms/square, 10⁹ to 10¹⁰ ohms/square, and 10¹¹to 10¹² ohms/square. If the coating is not acceptable (434), adetermination can be made to correct the coating (440). If the coatingcan be corrected the article can be recoated (412). If the articlecoating cannot be corrected (442), the part or portion of the articlecan be discarded (450)

FIG. 7 illustrates a non-limiting flow chart describing a method in anembodiment of the invention. The method includes determining (710)client or end user requirements for protecting a substrate with a coatedhousing based on the ESD or surface resistivity, percent transmittanceof light, gas permeability, coating hardness or any combination ofthese. The method can further include the step of contacting (720) acentral server/database to input the information for the client'srequirements, and coating (730) the housings with a diamond like carboncoating or a doped diamond like carbon coating to meet the clientrequirements. Measuring (740) the properties of the coated housing orcoated portions of the housing. The method can optionally furtherinclude the step of determining (750) a price for the coated housingsand optionally providing (760) the client with a price and time fordelivery of the coated housing(s).

Table 1 summarizes the gas permeation properties of doped DLC coated PCsamples in some embodiments of the invention. A 10 mil PC film with 120nm doped DLC coating on both sides, about 240 nm total doped DLC coatingas characterized by the XPS of FIG. 2A (untreated), was used as a samplefor the gas permeation tests. For comparison, the gas permeationproperties of uncoated PC film were also measured. The doped DLC coatinglayer on the polymer improved the permeation resistance properties ofthe PC film by more than 10 times, in some cases more than 80 times, insome cases more than 170 times, and in still other cases by more than350 times while maintaining transparency and surface resistivity usefulfor ESD (electrostatic charge dissipation; for example surfaceresistivity in the range of 10⁷ to 10¹⁴ ohm/square. The gas permeationtest on DLC coated PFA film was tried and showed no improvement whichsuggests that under the coating conditions used, open channels for gaswere present in the coating layer in these embodiments. The crack-likefeatures in microscopy are thought to be the open channels. As shown inTable 1 for the 10 mil thick polycarbonate film with 120 nm DLC coatingon both sides, in the case of H₂ gas, the permeability at 3 atmospheresdecreased by 179.9 times versus the uncoated PC film; for He gas at 6atmospheres pressure the permeability decreased by 84 times for thedoped diamond like carbon coated PC substrate in an embodiment of theinvention compared to the uncoated polycarbonate film.

The doped DLC films on a plastic in embodiments of the invention havebetter gas permeation resistance (smaller gas permeation coefficient)compared to the uncoated substrate. The gas permeation resistance isbetter than other reported diamond like carbon coatings. For example inU.S. Pat. No. 6,805,931 FIG. 12, polyacrylonitrile was reported to becoated with 231.5 nm and 400 nm DLC; the gas permeability to oxygendecrease by 33.8 times and the CO₂ permeability decreased by 37.4 timesfor the two films respectively compared to the polyacrylonitrile plasticuncoated.

TABLE 1 The gas permeability of the DLC coated PC film DLC coated PC H23 atm He 3 atm Permeability coefficient: 0.0591 (Barrers)** 0.0602(Barrers)** Diffusion coefficient: 0.4070 (10−⁸ cm²/s) 0.3659 (10−⁸cm²/s) Solubility coefficient: 0.0015 0.0016 (cm³/cm³ · cmHg) (cm⁸/cm³ ·cmHg) H2 6 atm He 6 atm Permeability coefficient: 0.0585 (Barrers)**0.1187 (Barrers)** Diffusion coefficient: 0.3778 (10−⁸ cm²/s) 1.6924(10−⁸ cm²/s) Solubility coefficient: 0.0015 0.0007 (cm³/cm³ · cmHg)(cm³/cm³ · cmHg) PC H2 3 atm He 6 atm Permeability coefficient: 10.6300(Barrers)** 10.0200 (Barrers)** Diffusion coefficient: 157.1322 (10−⁸cm²/s) 506.2420 (10−⁸ cm²/s) Solubility coefficient: 0.007 0.0002(cm³/cm³ · cmHg) (cm³/cm³ · cmHg)

A replicate test for the 120 nm diamond like carbon film of FIG. 2A(untreated—i.e. no plasma treatment) on both sides of a 10 mil PC filmmeasured a permeation coefficient for H₂ of 0.03 (Barrers); in thisembodiment the permeability coefficient was about 350 times less thanthe permeability coefficient of the uncoated PC film for H₂ gas.Permeation coefficients were also determined in replicate measurementson PC films coated on both sides with about 70 nm of doped diamond likecoating; the permeation coefficients measured were about 0.06 and about0.03 (Barrers).

The permeation coefficient was measured on a 13.66 cm² coated sample ofmaterial at about 25° C. The high pressure side was 223 mmHg; pressureincrease on the downstream side of the film was measured over about3.5×10⁵ sec.

Diamond like carbon coatings described in embodiments of the presentinvention, for example DLC, doped DLC, combinations of these, plasmamodified versions of these, may also be used for coating heat exchangerhollow tubes, fluid handling components, wafer handling systems, reticlehandling products.

The diamond like coatings on plastic substrates in embodiments of theinvention show good adhesion and the coatings may be used as anintermediate layer for further surface treatments like plasmaderivitization. For example to measure adhesion of the coating, Magic™tape from 3M could be attached as a small strip of about (1×1 cm) on theDLC coated films and rubbed using a gloved finger to remove anyentrapped air. The tape could be peeled off the DLC film and the amountof DLC coating transferred to the tape measured. From DLC coated PC,there is no noticeable amount of the coating on the tape (visualinspection). For ABS, the adhesion is quite good and almost the same asPC. The PFA showed a little bit poor adhesion (˜10% transfer) and PPshowed even higher transfer. PP substrate has quite different surfaceroughness on each side. From rougher side, almost 50% of the coating wastransferred to the tape and from smooth side less than 10%.

The diamond like carbon coated plastics in embodiments of the inventionare chemically stable. For example, small strips of DLC coated PC film(20 mil thickness film with 120 nm DLC coating on both sides) were cut(5 mm width and 2.5 cm length). One piece was rubbed with a IPA soakedlab tissue (Kimwipes) about ten times. A cross mark was added to one endof the strip by a razor blade and the sample was placed in 10 mL of IPAfor three days. In another test, two pieces were placed in 10 mL ofwater and 1% surfactant (Alfonic A10) solution of water respectively.Both were boiled for 2 min using a lab microwave. Two samples stayed inthe same liquid for three days. The three samples were taken out andrinsed with water and wiped to dry. Surface resistances were measuredand all showed the same surface resistance before the test. (10¹¹ohm/square). Tape tests were done using a 3M Magic™ tape as describedpreviously and none of the coating (visual inspection) was transferredto the tape.

An Si wafer was used as a substrate for the DLC coating purity test; Siwafers are known to be very clean and so the purity of the overlyingcoating could be measured in this way.

For outgassing organics, each wafer was placed in a clean dish with aTenax tube and allowed to stand for 7 days at room temperature. A Tenaxtube was also placed in an empty dish to provide a background blank forthe experiment.

The total outgassing organics measured for the DLC coated wafer did notdiffer significantly from the uncoated control wafer. Major organicspecies (or generic classes of organic species) detected for bothsamples were ketones and aliphatics. Only three species were observed inthe DLC coated wafer that were not observed in the uncoated controlwafer. These included a siloxane and nitrogen-containing compound. Table2 shows the results.

TABLE 2 Outgassing organics. Category Uncoated - - - Test Wafer DLCCoated Parameter Units Method (Control) Wafer Chemical Outgassing Σ μgFGTM 1350 4.6 4.7 Organics (7 Day, RT) (ATD-GC/MS) Tenax TA

Sample preparation for anions and metals analysis of the wafers orcoated wafers was performed by placing 25 ml aliquot of ultrapure DIwater into a clean, pre-leached container and then drawing up thealiquot with a pipette and rinsing the appropriate side of the waferthree times. The rinse procedure was performed separately for eachwafer. The resulting rinse for each wafer was split, with one portionanalyzed for anions via ion chromatography, and the other portionacidified and analyzed for metals via inductively coupled plasma massspectrometry (ICP/MS).

Anions detected for the DLC coated wafer were not significantlydifferent than those detected for the uncoated control wafer. Theuncoated control wafer revealed low levels of only nitrate and sulfate,while the DLC coated wafer exhibited low levels of only nitrate. Allother anions for both samples were below detection limit.

TABLE 3 Aqueous rinse anions. Category Uncoated - - - Test Wafer DLCCoated Parameter Units Method (Control) Wafer Chemical Aq. Rinse 25 mLRinse Anions (IC) Acetate ng  d.l. <200 dl dl Br⁻ ng d.l. <25 dl dl Cl⁻ng d.l. <25 dl dl F⁻ ng d.l. <25 dl dl HCO⁻ ng  d.l. <100 dl dl NO₂ ⁻ ngd.l. <25 dl dl NO₃ ⁻ ng d.l. <25 35 49 SO₄ ²⁻ ng d.l. <25 38 dlPhthalate ng d.l. <25 dl dl PO₄ ³⁻ ng d.l. <25 dl dl

Trace metals analysis for the DLC coated wafer and the uncoated controlwafer showed a lack of aqueous rinse trace metals in both samples. Theonly trace metal observed in either sample was nickel at 19 ng in theuncoated control wafer. All other trace metals for both samples werebelow detection limit.

The doped DLC films in embodiments of the present invention outgaswithin 2% of the base substrate, and can have ion and metals content ator below those measured in Tables 3 and 4.

TABLE 4 Aqueous rinse trace metals. Category Uncoated - - - Test WaferDLC Coated Parameter Units Method (Control) Wafer Chemical Aqueous RinseΣ ng 25 mL Rinse 19 0 Trace Metals (ICP-MS) Ag ng 11 dl dl Al ng 5.5 dldl As ng 7.0 dl dl Au ng 40 dl dl B ng 18 dl dl Ba ng 9.8 dl dl Be ng7.3 dl dl Bi ng 9.5 dl dl Ca ng 9.3 dl dl Cd ng 9.0 dl dl Co ng 2.8 dldl Cr ng 4.3 dl dl Cu ng 3.3 dl dl Fe ng 9.0 dl dl Ga ng 8.0 dl dl Ge ng8.0 dl dl Hg ng 11 dl dl K ng 11 dl dl Li ng 4.5 dl dl Mg ng 8.3 dl dlMn ng 4.5 dl dl Mo ng 7.5 dl dl Na ng 14 dl dl Nb ng 6.0 dl dl Ni ng 3.819 dl Pb ng 10 dl dl Pt ng 9.0 dl dl Sb ng 7.3 dl dl Sn ng 8.3 dl dl Srng 8.8 dl dl Ta ng 7.8 dl dl Ti ng 11 dl dl Tl ng 9.8 dl dl V ng 7.5 dldl Zn ng 8.0 dl dl Zr ng 7.8 dl dl

The hardness of the doped DLC films in embodiments of the invention canbe measured by pencil hardness (ASTM D3363). It is a hardnessmeasurement that has been used for paint and coating. It involvesscratching the surface using various lead grades and determining theweakest lead making a scratch in the surface. Human fingernail has ahardness of around 2H and this method is good for measuring the scratchresistance of a surface.

The hardness of the doped DLC films in embodiments of the inventionapproximate those of the underlying polymeric substrate. Films are sothin that mechanical properties are dominated by the mechanicalproperties of the underlying substrate by gross deformation. Forexample, a DLC layer on PC film is so thin and the PC film is quitesoft, around 2B, that a pencil hardness test results in failure of theDLC film due to the soft underlying PC film. In contrast, a DLC of thepresent invention coated on an Si wafer was a good sample for measuringthe hardness of the DLC film; the DLC layer on Si wafer is harder than8H.

The DLC coating layer surface can be modified because it has a carbonstructure on the surface. The doped DLC structure is a network that hasa diamond like carbon and graphite structure. The surface treatment isstable, which means it does not change much according to the time asshown in Table 5. In some embodiments the surface treatment results in acontact angle that is 30 degrees to 40 degrees less than the contactangle with water of the untreated substrate after 3 weeks in ambientair; in other embodiments the surface treatment results in a contactangle that is 25 degrees to 40 degrees less than the contact angle withwater of the untreated substrate after 10 weeks in ambient air; in stillother embodiments the surface treatment results in a contact angle thatis 20 degrees to 30 degrees less than the contact angle with water ofthe untreated substrate after 16 weeks in ambient air. Without wishingto be bound by theory, the stability of the contact angle of thechemically modified doped DLC films may be due to the functional groupson the surface not having enough mobility for surface rearrangement, theorganic or other contaminants from the underlying substrate cannot maskthe surface groups, or a combination of these.

The DLC coating can be modified by a plasma treatment. For example, aDLC coating of FIG. 2A was subsequently treated by an oxygen plasmatreatment method and the contact angle change was measured over time.Table 5 shows the result; the water spread right after the treatment andthe contact angle increased over the time but did not recover completelywithin the time range studied. FIG. 2B (treated) characterizes theplasma modified film by XPS.

TABLE 5 Contact angle change of the surface treated DLC coating. DLC onSi wafer DLC on PC Untreated 65 ± 5 65 ± 5 After treatment spread spreadAfter 3 weeks (in the air) 25 ± 8 32 ± 4 After 10 weeks (in the air) 25± 8 40 ± 3 After 16 weeks (in the air) 35 ± 3 45 ± 2

XPS analyses of a doped DLC film coated on polycarbonate, spectra (210)in FIG. 2A, and an oxygen plasma treated doped DLC film coated onpolycarbonate, spectra (220) in FIG. 2B, were performed. The amount ofoxygen was increased by the oxygen plasma surface treatments asillustrated by the increase in the intensity of the O 1s peak near 534eV from (210) to (220) and by the difference in the atomic percentratios for the two spectra. In XPS spectra of the untreated diamond likecarbon coating (210) the atomic percent (%) of carbon (C1s) is 82.2%;for nitrogen (N1s) it is 9.7%; for oxygen (O1s) it is 8.1%. In thetreated diamond like carbon coating in the embodiment illustrated inspectra (220), the atomic percent (%) of carbon (C1s) is about 71.6%;for nitrogen (N1s) it is about 8.0%; for oxygen (O1s) it about 20.4%.The atomic ratios are not limited to these and can varied by changingthe deposition or subsequent treatment time as well as the mixture ofgases or reagents used to deposit the coating and or to subsequentlytreat the coating surface. The oxygen and nitrogen in the untreatedsample may be due to the doping process of the doped DLC coating.

DLC coatings in embodiments of the invention may be used on fluidhandling parts to reduce static charge. For example, such a coating mayhelp in reducing static charge build-up on a spray nozzle orperfluorinated tubing used in wafer manufacturing or heat exchangers. Inthese embodiments the coating can have a surface resistivity thatprovides static dissipation, a surface resistivity in the range of fromabout 10⁷ ohm per square to about 10¹⁴ ohm per square, but the gaspermeation coefficient can be similar to about 0.1 times thepermeability of the underlying polymer.

PC has the one higher surface energie out of the polymers used becauseit has more polar groups, hydroxides, carbonyl, and the like. It may bepossible to pretreat other polymers with plasma to provide them with ahigher surface energy and provide similar bonding (Van der vaals, Hbonding). The DLC coating can also be used as an initial layer forfurther surface treatment because the surface can be modified usingvarious methods and the treated surfaces show a long service time.Optionally the surface of the plastic material can be activated toenhance adhesion of the diamond like carbon coating to the plastic. Forexample, the plastic surface may be activated by a plasma with aninorganic gas such as but not limited to argon or oxygen gas, or othersuitable gas (Cl₂, water, NH₃, air, nitrogen).

The uniformity of the coating can vary by less than about 50% across thesubstrate, in some embodiments less than about 10%. The less variationthe more uniform the surface resistivity (ESD) and gas permeationresistance or gas permeability coefficient.

The DLC coatings in embodiments of the invention can be made by a vaporphase deposition. In some embodiments the temperature of the substratecan be controlled to reduce thermal stress and differential thermalexpansion between the coating and substrate during and following thedeposition process. This can provide improved gas permeation resistanceand more uniform ESD. In some embodiments the substrate can be coatedbelow a temperature of about 70° C.

Various portions of wafer carrier surfaces, for example where control ofESD or where diffusion or permeation of contaminants into the wafercarrier is an issue, can be coated in embodiments of the invention.Different parts of the carrier can be coated with different amounts ofcoating to tailor the ESD properties, transparency, or other properties.Wafer carriers, FOUPS, wafer shippers, and other similar substratecarriers for environmentally sensitive materials can be DLC or doped DLCcoated. Such carriers can be prepared by the methods and materials suchas but not limited to those disclosed in U.S. Pat. No. 5,255,783, thecontents of which are incorporated herein by reference in theirentirety. Various portions of reticle pod surfaces where control of ESDor where diffusion or permeation of contaminants into the reticle pod isan issue can be coated in embodiments of the invention. Different partsof the reticle pod can be coated with different amounts of coating totailor the ESD properties and transparency. Reticle pods can be preparedby the methods and materials such as those disclosed in U.S. Pat. No.6,338,409 or U.S. Pat. No. 6,498,619, the contents of which areincorporated herein by reference in their entirety. Portions of carrierscan be coated with different amounts of DLC coating, doped DLC coating,or modified versions of these coatings to protect the environmentallysensitive substrates from electrostatic discharge, light catalyzed orlight driven reactions.

Although the present invention has been described in considerable detailwith reference to certain preferred embodiments thereof, other versionsare possible. DLC and doped DLC coatings in embodiments of the inventionhave quite unique properties such as low friction coefficient, highscratch resistance, high barrier properties and good thermalconductivity. Chip trays, matrix tray, and test sockets can have all ora portion of their surfaces coated with the coatings of the presentinvention. Wafer handling product (low friction reduces particlegeneration, low permeation improves the bad effect due to oxygen andwater). For polymeric heat exchangers (good thermal conductivityimproves the performance and low permeation reduces the diffusion ofdangerous chemical vapor such as HF and HCl) a DLC coating layer can beapplied to outside and/or inside of heat exchanger hollow fiberdepending on the chemical compatibility. In fluid handling system andcomponents, low permeation decreases the leak of dangerous chemical andvapor. Base coating for further surface modification (DLC can bemodified by various technique including plasma treatment). Embodimentsof DLC, doped DLC, or treated versions of these can be applied to liquidand/or gas filtration membranes to control permeation, thermalconductivity and/or surface properties

Therefore the spirit and scope of the appended claims should not belimited to the description and the preferred versions contain withinthis specification.

What is claimed is:
 1. An article comprising: a thermoplastic and an adherent diamond like carbon coating on one or more surfaces of said thermoplastic, the adherent diamond like carbon coating being a doped diamond like carbon that further comprises 8.1 atomic percent or more of oxygen and 9.7 atomic percent or less of nitrogen, said adherent diamond like carbon coating has a permeability coefficient for helium gas that is at least 10 times less than the permeability coefficient for helium of said thermoplastic, the diamond like carbon coating has a surface resistivity of from about 10⁷ to about 10¹⁴ ohm/square and said adherent diamond like carbon coating has a transmittance that is 0% to 70% less than the transmittance of said thermoplastic to light in the range of 300 nm to 1100 nm.
 2. The article of claim 1 where the article is an enclosure for environmentally sensitive substrates that comprises at least a portion of a carrier from the group consisting of: a carrier for wafers; a carrier for flat panel displays; and a carrier for lithographic reticles.
 3. The article of claim 1 where the surface resistivity of the adherent diamond like carbon coating provides a surface resistivity in the range of 10⁸ ohm per square to 10¹² ohm per square.
 4. The article of claim 1 where the surface resistivity of the adherent diamond like carbon coating provides a surface resistivity in the range of 10⁹ ohm per square to 10¹² ohm per square.
 5. The article of claim 1 where the adherent diamond like carbon coating has a variation of surface resistivity that is less than 10² ohm per square.
 6. The article of claim 1 where the adherent diamond like carbon coating has a variation of surface resistivity that is less than 10¹ ohm per square.
 7. The article of claim 1 where the adherent diamond like carbon coating has an XPS spectra that has a carbon peak, an oxygen peak, and a nitrogen peak.
 8. The article of claim 7 where the XPS spectrum of said adherent diamond like carbon coating includes a carbon peak at about 284 eV, an oxygen peak at about 532 eV, and a nitrogen peak at about 399 eV.
 9. The article of claim 1 where the adherent diamond like carbon coating is further treated by a plasma, a reactive gas containing plasma, or corona discharge, an oxygen containing plasma, to form a hydrophilic adherent diamond like carbon coating.
 10. The article of claim 1 where the article is a substrate carrier. 